Party-line telephone-exchange.



PATBNTED NOV. 19, 1907.

S. A. NORSTROM. PARTY LINE TELEPHONE EXCHANGE.

APPLICATION FILED JULY 14, 1905.

SAMUEL A. NORSTROM, OF CHICAGO, ILLINOIS, ASSIGNOR TO CASPER L. REDEIELD, OF

CHICAGO, ILLINOIS.

PARTY-LINE TE LEPHONErEXCHANGE Specification of Letters Patent.

Patented Nov. 19, 1907.

Application filed m 14. 1905. Serial No. 269.599.

To all whom it may-concern:

Be it known that I, SAMUEL A. NORSTROM, a citizen of the United States of America, and a resident of Chicago, county of Cook, and

State of Illinois, have invented certain new tion of the devices at the local station.

The accompanying drawing illustrates the devices at two local stations, said devices being in their normal position. These stations are connected to a central office by means of the wires 1 and 6. The devices at the central are the ordinary ones among which are a battery, a contact making device for sending impulses from the battery oven-the line or over one side of the line and ground, and

means for reversing the direction of the current. These central office devices may be of any of the well known kinds and form no art of the present invention.

At each local station there is a switching mechanism operated by the magnet AA, which magnet has a polarized armature A Adjacent to this magnet is a ratchet wheel B which is adapted to be advanced from its normal position in the ordinary manner.

The advance of the ratchet wheel B is by means of a pawl A on a lever A connected to the armature A. A holding pawl B prevents a return of the wheel until released. On the lever A is a projection A adapted to strike and lift the pawl B when the lever A is moved toward the right. On the pawl A is a curved rojection A which rests on a pin A andis a apted to raise pawl A"-from the ratchet wheel B when the lever A is moved to theright. The result of this construction is that when impulses are sent through the magnet AA in one direction it moves the lever A to.the left and causes the ratchet wheel to advance step by step. When an impulse is sent in the opposite direction it moves the leverA to the right causing a release of the ratchet wheel so as to permit it to return to its normal position.

On the spindle which supports the ratchet wheelB is a contact maker P and a cam C which move with the wheel. Adjacent to the wheel B is a late D provided with a series of holes D in the path of the contact maker P. At the first station on the'line a contact pin is placed in the first hole D, at the second station a. pin is laced in the second hole, and so on. en the contact maker P is advanced it will touch in passing its contact pin and thus make an electrical connection with the plate D which is insulated from the other parts.

The drawing shows the switchin mechanism withenough holes to be suitable for thirteen stations on the line. In such a case the contact maker P is set back so that it does not reach the position of the first holeD until the fourteenth forward step of the ratchet wheel. At the fourteenth step the contact maker P- for the first station will strike its in, at the fifteenth step the contact maker or the second station will strike its pin, and

so on.

Adjacent to the cam C are three springs 13, 14 and 23, the center one of which engages the cam. This cam has three steps, and when in its normal position the spring 14 rests on the center step and is not in contact with either of the other springs. When the switching mechanism advances one step the spring 14 rests on the lower step of the cam and then engages the inner spring 13. This position is maintained until the fourteenth step when the cam pushes the center spring :14 out into contact with the outer spring 23.

This outer position is then held during any further advance of the wheel B.

At each local station there are a receiver R, a hook H with adjacent contact springs, a ringer Q, a generator G, a condenser W, and electrical connectionsas shown.

When the operator at the central oflice wishes 'to place two .stations on the line in telephonic connection with each other, she beglns by connecting the two lines 1 and G to her battery when a current flows from the battery as follows: -12 of each station 3AA45-6 battery. This is an impulse in the direction which will advance the ratchet wheels B and is re eated a reuired number of times. At t e first step t e cams C move so that the CGIIiJBl s rings14 engage the inner springs 13. Int 's position, by connecting her signaling device between ground and the line 6, the operator may simultaneously signal all stations on the line as follows :from ground at the central to ground at each station 78-910 1 1Q-12-1314 15 4 -5 6 -back which had their switching mechanisms re- The result is to release the first switch and to central. This is not what is ordinarily done but is possible at any timeduring the first thirteen steps of the switching mechanism. At the fourteenth step the cams C break the connections between springs 13 and 14, thus breaking the signaling connec-" tions for all stations. At this step the first station has its contact maker P on its con-v tact pin located in the first hole Dfibut as no other station has a pin in its first hole, no

other station has this kind of a connection.

The wire connecting the spools of the magnet AA is electrically connected to the lever A and through this lever, its pawl A and the wheel B is in electrical connection with the contact maker P.

If it is the first station that is wanted then, at the fourteenth forward step of the ratchet Wheel B, the operator connects her battery betweenline 1 and ground sending an impulse from ground at central to ground at the first station 7816D contact pin in first hole D. P B A -A? A3 2 1 battery. This is an impulse in the opposite direction to the original operating impulse and occurs only at the first station because that is the only one which has its contact maker P in contact with a pin in the plate D.

permit it to return to normal position. j In returning the contact maker P breaks this circuit as soon as it starts to. return, but a branch is closed by'the armature A engaging the spring 17, so that the current flows-from 8 through A A A etc., as before. This holds the release circuit for this particular station until the operator breaks it at the central office. The operator then advances the switching mechanisms as before, and when she comes to the second station wanted, she releases'the switching mechanisms for that station in the same way as just described for the first station. She may then advance all of the switchesv one step more or move them to the end of. their forward movements. In either case all of the switches, except the two which were returned'to their normal positions afterhaving been advanced fourteen or more steps, have their contact makers over the plate D and as a consequence have their Cams 0 moved far enough to break their ringing circuits-as before explained. In the case of the two stations leased, the contact'makers lie between their normal positions and the first part of the plate I), and as a consequence their cams are in a osition to leave their ringing circuits close at 13 and 14. Having arrived at this point, the central oifice operator signals these two stations in the same manner as explained as possible for all stations, whereupon the called subscribers remove their recuit between subscribers is asfollows:Beginning at the receiver of station No. 1, R

20H21565 of station No. 1 21201918R. All of those Stations not called have their cams 0 advanced so that'the springs '14 are pushed out into connection with springs 23. In case a subscriber at one of these stations should re- W hen this 1 signal is received, the operator sends an impulse over the line precisely as described foradvancing the switching mechanisms, except that she reverses the direction of the current. The result is to release all of the switching mechanisms in the same manner as previously described for one of them.

With its switching mechanism-in its normal position, each station is in telephonic connection with the line and the subscriber may talk to the central office by removing his receiver and turning his generator crank to send a signal.

As the subscriber has no control over the movements of his switching inecl1anisn1,eacl1 is cut out at the fourteenth forward step and is not again in telephonic connection with the line unless the operator. releases his switch so that it may return to its normal position; In exchanges of smaller capacity, there would be a less number of steps before the cutout came, and in exchanges of larger capacity, a greater number of steps.

What I claim is 1. The combination with the switching mechanisms of a series of stations on a party series of switching mechanisms, and means for giving them asimultaneous advance step by step from normal position, of means by which selected ones of said switching mechanisms may be moved so as to disph ce them from being in step with the other switching mechanisms, and telephonic connections controlled by the positions into wvhich saidswitching mechanisms are moved.

ceivers. Ii the stations called are those shown in the drawing, then the talking ciri 3. The combination with'a'partylinc hav- ,mg a series of local stations thereon, and

means controlled from a central office for 'neous advance of all of said switching mechanisms, of electrical connections closed by theldifierent switching mechanisms in suc-H cession, and means by which upon an elec-' trical impulse being sent through a closed connection, the switching mechanism which closed it will be automatically returned to its normal position.

5. The combination with a series of switching mechanisms, and means for advancing them simultaneously step by step from normal position, of means controlled from a central office for displacing a selected oneof said switching mechanisms so that it will not be in step with the other switching mechanisms.

6. The combination with a party line, and a series of switching mechanisms adapted to I be advanced by impulses flowing in one direction over the line and to be released by impulses flowing in the opposite direction, of

v means by which an impulse in the release direction is made effective 11 on a" selected one only of said switching mec anisms.

7. The combination with a party line, and a series of switching mechanisms arranged to be advanced or released'according to the direction'in which impulses flow over the line, of means by which an impulse in the release direction is made efi'ective ,upon all switching mechanisms simultaneously, and additional means by which an impluse in the release direction ismade effective upon a selected one only of said switching mechanisms;

8. The combination with a series of electromagnetic' switching mechanisms connected to a party line, and means by which said switching mechanisms are advanced or released according tothe direction of impulses flowing therethrough, of means by which upon sending impulses through said mechanisms so as to cause their simultaneous advance electrical connections will be completed thereby in succession so that impulses in the release direction may be sent therethrough individually.

Signed at Chicago, Ill. this 7th day of July SAMUEL A. NORSTROM. Witnesses:

A. L. BUCHANAN, C. L. REDFIELD. 

